encryptString.java

//Write a program to encrypt the line entered by the user. Encryption is performed
//    by replacing all occurrences of the letter ‘i’ by ‘e', all occurrences of the letter ‘e’
//    by the letter ‘a’, and all occurrences of the letter ‘a’ by the letter ‘i’. For example,
//    if the user enters the line: The ear is big. Then the output from the program is: Tha
//    air es beg. Both upper case and lower case of aforementioned letters must be
//    encrypted.

import java.util.Scanner;

/**
 * Copyright ${COPYRIGHT}.
 */

import java.util.regex.Pattern;

public class encryptString {

  public static void main(String[] args) {
    String replaced = "";
    Scanner kb = new Scanner(System.in);
    System.out.println("Please enter string to encrypt: ");
    String str = kb.next();

    //String str = "";
    for (int i = 0, n = str.length(); i < n; i++) {
      if (str.toLowerCase().charAt(i) == 'i') {
        replaced += 'e';
      } else if (str.toLowerCase().charAt(i) == 'e') {
        replaced += 'a';
      } else if (str.toLowerCase().charAt(i) == 'a') {
        replaced += 'i';
      } else {
        replaced += str.charAt(i);
      }

    }
    System.out.print(replaced);
  }
}